Mitral valve is located at the left atrioventricular orifice, and is consisted of five parts which are the valve annulus, the valve leaflets, the chordae tendineae, the papillary muscles, and the connecting junction, an exact name of which in anatomy is mitral apparatus or mitral complex.
Tricuspid valve is located at the right atrioventricular orifice, with three triangular like sail-shaped valves. The base of the valves is attached to the fibrous annulus at the atrioventricular orifice. By function, the fibrous annulus, the valves, the chordae tendineae, and the papillary muscles can be seen as a tricuspid valvar complex.
Mitral regurgitation can be divided into the following two kinds. 1. A rheumatic heart mitral regurgitation, mainly caused by mitral insufficiency, can cause a reverse flow of blood to mix different bloods, resulting in cardiac pumping and oxygen transfer function decrease. 2. A non-rheumatic mitral regurgitation usually referred to varying degrees of the mitral regurgitation caused by abnormalities, other than rheumatic valve diseases, of the mitral valve itself and its surrounding anatomical structures. The non-rheumatic mitral insufficiency has many causes, and the common causes are: leaflets prolapse, papillary muscle insufficiency or rupture of chordae, left atrial myxoma, valve annulus calcification, congenital valve malformation, infective endocarditis, and so on. The mitral regurgitation can also be divided into three types, functional, degenerative, or mixed. The most common one is the degenerative and the functional mitral regurgitations. The functional mitral regurgitation is generally secondary to a left ventricular wall motion dysfunction, a left ventricular dilatation, and a papillary muscle dysfunction, generally found in patients with heart failure. This part of patients also has, secondary to a coronary heart disease, ischemic mitral regurgitation and non-ischemic heart muscle disease related mitral regurgitation. The degenerative mitral regurgitation disease is generally deemed to be pathological changes in the valve structure, or pathological changes of the structure below the valve, including an abnormal extension or rupture of the chordae.
Tricuspid regurgitation is usually caused by a pulmonary hypertension, a right ventricular dilatation, and a tricuspid annulus expansion. After the tricuspid regurgitation occurs, the symptoms of a right heart failure such as fatigue, ascites, edema liver pain, indigestion, anorexia, and so on become worse. Tricuspid insufficiency is mainly divided into functional tricuspid insufficiency and organic tricuspid insufficiency. The organic insufficiency of the valves caused by rheumatic fever is rare. The major cause is the functional insufficiency, and the most common cause is the right ventricular dilatation and the tricuspid annulus expansion caused by the pulmonary hypertension, resulting in tricuspid valve relative insufficiency, however the valves themselves are normal in structure, such as the rheumatic mitral valve disease, the congenital cardiovascular disease, and the pulmonary heart disease.
Traditional treatment for the mitral regurgitations and tricuspid regurgitations includes drug therapy for the mild to severe regurgitations, and surgical approach corresponding to surgical indications. Among them, the surgical approach also includes mitral valve replacements and tricuspid valve replacements, and mitral valve repairs and tricuspid valve repairs. For the simple mitral regurgitation, only 30% of the patients have the need of the mitral valve replacement, the rest only need the mitral valve repair. In the surgical approach, the typical thoracotomy and open heart surgery are too invasive, which need to establish a cardiopulmonary bypass, with higher incidence of complications and risk of infection. To reduce the risk of surgery, transcatheter interventional replacement and repair methods are developed.
According to the report of an article, [Enriquez-Sarano M, Schaff H V, Orszulak T A, et al. Valve repair improves the outcome of surgery formitral regurgitation: a multivariate analysis [J]. Circulation, 1995, 91 (4): 1022-1088], the visible replacement surgery has a higher overall mortality rate and a lower survival rate.
TABLE 1Comparison of mortality rate and complications after a mitral valvuloplasty and a mitral valve replacement (multicenter) Mitral Mitral valvevalvuloplasty replacement POverall surgical death rate 2.6% 10.3% 0.0002 Death rate for age <75 years 1.3%  5.7% 0.036 Death rate for age >75 years 6.8% 30.8% 0.0005 5-year survival rate  92%   72% 0.003 10-year survival rate  69%   58% 0.0004 Thrombosis incidence 1.8%  8% 0.03Postoperative cardiac function  54%   49% 0.05 (left ventricular ejection fraction) 10-year no surgery rate  75%   80% 0.47 Endocarditis within 4.5 years 0  2.8% 0.08
The current problems to be solved for the transcatheter treatment of the valve regurgitation are as follows: the implantation volume is to be reduced under the premise of as far as possible to ensure the anti-regurgitation effect; the anti-regurgitation device must be accurately positioned and firmly fixed at the location needed to be treated; the anti-regurgitation device is required to minimize an effect on normal function of the rest valve leaflets; the anti-regurgitation device needs to adapt to the differences in the physiological structures of the valve annulus. The following lists technical points of different anti-regurgitation devices in prior art.
WO 2006037073 A2 describes a therapy method of mitral valve repair using a mitral clip to suture a center or a corner region of the mitral valve, but this technique cannot be applied to the following two types of patients: one of which has a systole coapting gap between valve leaflets>10 mm, as cannot accurately synchronize the movements of the two valve leaflets; and the other of which has a severe thickening and calcification of the structure below the annulus, due to the breaking risk of the chordae for the pressure increase of the chordae, the valve leaflets, and the valve annulus.
US2009105751A1 and CN101902975 describe an apparatus for repairing a valve leaflet in a pulsatile heart of a patient, comprising a handle assembly, a capture assembly, and a needle. A valve leaflet is captured through the capture assembly, and the needle passes through the valve leaflet to limit the movement of the prolapse valve leaflet to achieve the anti-regurgitation effect. But in operation, this technique needs to seize the moving valve leaflet, the operation is difficult and time consuming, and easy to cause laceration on the autologous valve leaflet.
US20130023985 describes an implant, an implant system, and a method for treating valve mal-coaptation and other valve diseases. The implant includes a coaptation assist body, and the length of the superior edge of the coaptation assist body contacting the autologous annulus is 25-35 mm, which is equal to the distance between the first commissure and the second commissure. The length of the coaptation assist body between the superior edge and the inferior edge is 50-60 mm. On the coaptation assist body, an anchoring device can be optionally provided. In one claim, it defines that a part of the coaptation assist body is cone shaped, and in another claim, besides defining the length of the superior edge of the coaptation assist body contacting the autologous annulus is 25-35 mm, it further defines that a height of the leaflet coaptation perpendicular to the valve annulus is 35-45 mm, a height of the non-coaptation of the ventricle in the direction perpendicular to the annulus is 25-35 mm, and an curve radius of the coaptation is within 35-45 mm. The limiting for the length of the superior edge contacting the autologous annulus of the system is only for the overall repair of the anterior leaflet prolapse or posterior leaflet prolapse of the mitral valve, and the repair of an overall valve leaflet prolapse of a part of the tricuspid valve. It also shows that the inferior edge of the coaptation assist body covers at least a majority of the leaflets, and the coaptation has a specific curve requirement. This technique cannot accommodate the repair of the prolapse of a small part of the valve, or the repair of smaller valves such as the aortic valve. While repairing the mal-coaptation position, it sacrifices the rest normal valves. In summary, the disadvantages include: first, it clearly describes that the length of the superior edge of the coaptation assist body equals the distance between the first commissure and the second commissure, and thus it is applicable only to the overall repair of the valve leaflets, the repair area including not only the leaflet prolapse part but also the normal part of the leaflet; second, the length of the annulus varies widely among persons, and before the actual operation, the distance between the first commissure and the second commissure is unpredictable, the product design is hard to have an exact match; third, the shape of a part of the coaptation assist body is cone shaped, striving to match the cone shape of human leaflets, and for the same reason among different persons, the exact match is difficult to achieve; fourth, the design is not suitable for the repair of the commissural leaflets prolapse.
In CN103338726A, a method for treating mal-coaptation of a the patient's heart valve is described, which comprises introducing an implant into the heart while the implant is in a first configuration, deploying the implant from the first configuration to a second configuration within the heart, the implant in the second configuration having a coaptation assist body with first and second opposed coaptation surfaces; and supporting the deployed implant so that the coaptation assist body is offset from the axis of the heart valve along the coaptation zone. In one claim, the method also includes: selectively deploying a first anchor at a first target location near the first commissure (the first commissure is at a first junction of the first and second leaflets of the heart valve); selectively deploying a second anchor at a second target location near the second commissure (the second commissure is at a second junction of the first and second leaflets of the heart valve); and introducing a coaptation assist body into the heart. In another claim, it describes the implant comprises a coaptation assist body, a first anchor, and a second anchor, the coaptation assist body has an axis and first and second opposed major coaptation surfaces, each coaptation surface extending laterally between a first lateral edge and a second lateral edge of the coaptation assist body; the first anchor selectively deployable at a first target location of the heart near the first commissure and coupleable to the coaptation assist body so that the first lateral edge is oriented toward the first commissure; the target location of the second anchor is near the second commissure. In another claim, it further limits that the axis of the implant extends along the axis of the valve, and the first and second lateral sides of the coaptation assist body extend along the curve of the coaptation zone of the heart valve, wherein the coaptation assist body of the supported implant is sufficiently laterally conformable so that engagement between the implant and the heart laterally bends the coaptation assist body between the edges toward the curve defined by the coaptation zone of the heart valve. The above described claims limit that the target positions of the anchors are near the first and second commissures, and the overall coaptation assist body is sufficiently laterally conformable to the heart valve. This technique does not adapt for a partial valve prolapse syndrome, and has the following disadvantages while exhibiting the anti-regurgitation effect. First, the “supporting the deployed implant so that the coaptation assist body is offset from the axis of the heart valve along the coaptation zone” means that as the implant naturally deploys, the coaptation assist body shrinks along a centerline, which requires the coaptation assist body to be cone shaped. Second, the coaptation assist body covers the non-prolapse normal valve, and in the long-term movement, is likely to cause an adhesion, sacrificing the normal operation of the normal part of the valve. Third, during the opening and closing processes, the autologous valve near the autologous annulus and toward the apex of the heart has a smaller motion amplitude than a valve leaflet located close to the cusp, and is easily adhered to the heart valve assist body which is sufficiently laterally conformable and contact to the autologous valve. This location is different from the superior edge of the coaptation assist body, which is at the location of the valve annulus. The location of the valve annulus should grow together with the autologous annulus during the long-term implantation to improve the fixation effect. However, once adhesion occurs to the autologous valve near the autologous annulus and toward the apex of the heart, the valve leaflet movement is affected, easily causing a second regurgitation, which leads failure of the anti-regurgitation treatment. Fourth, the valve annulus has different size for different person, leading the requirement for producing numerous specifications of products.
US20130325110A1 describes a beating heart method of delivering a valve leaflet coaptation assist prosthesis to treat the mitral and tricuspid regurgitations. The method comprises using a flexible rail to delivering a ventricular anchor from atrium through autologous valve to the right ventricle to perform the anchoring; using a catheter to deliver the prosthesis and adjust the location of the prosthesis at the tricuspid annulus till the regurgitation decreases; fixing the position of the catheter relative to the flexible rail and securing the catheter to the subclavian vein. This method of delivery can adjust the position of the prosthesis to adapt to different regurgitation position, and has a disease adaptability, but the location of the fixation position at the subclavian vein is far away from the valve annulus position, easily leads unstable of the fixation and a prosthesis displacement after the fixation.
The current clinical results show that there is no ideal product for the treatment of the valve regurgitation. The main reason is that the mitral annulus, the tricuspid annulus, etc. have special physiological structures, and there is a complex physiological environment at the position below the annulus, resulting in difficulty of accurate positioning and fixing of the products. In addition, the valve prolapse has different degree and location. For example, some of the patients have the mitral insufficiency caused by an anterior leaflet prolapse, and some of the patients have the mitral insufficiency caused by a commissural leaflets disease. During the treatment of the insufficiency at the pathologic change location, the above-mentioned techniques also interfere with the physiological structure of the rest normal mitral valve, lacking of disease adaptability. In summary, although the techniques described above have respective effects on the valve repair, there is a need for the prosthesis in the field of surgical treatment of valvular insufficiency, and the prosthesis is position adjustable, positioning accurate, and anchoring secure, that is able to deal with a variety of different degrees and locations of the lesion.